Power actuated tool



Jan. 10, 1967 w. E. OSBORNE POWER ACTUATED TOOL Filed April 30, 1965 INVENTOR. WILL IAM E. OSBORNE BY W. 21.5%;

A T TORNEV United States Patent Ofiice 3,297,224 Patented Jan. 10, 1967 3,297,224 POWER ACTUATED TOOL William E. Osborne, East Haven, Conn., amignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Filed Apr. 30, 1965, Ser. No. 452,183 8 Claims. (Cl. 227-) This invention relates to tools for driving various members such as hammers, punches, cutters, or fasteners such as studs, pins, and the like into wood, steel, masonry, or concrete, and more particularly, relates to such tools actuated by power means such as an explosive.

In the operation of some conventional power tools, it is necessary for the operator to open the breech to permit ejection of the spent cartridge, and then, reverse the position of the tool, and load the fastener member into the muzzle end of the barrel. This is a very cumbersome procedure which results in wasted time between each firing.

Another disadvantage present in some tools is the possibility of the inadvertent projection of the piston member into free flight so as to be dangerous.

Yet another disadvantage of conventional tools is the difficulty of properly extracting a cartridge with an attendant reduction in speed and operation. Some tools relied upon compressed air being developed in the cylinder between the piston head and the cartridge to cause ejection. However, in some cases, as the piston is returned to its firing position, the compressed air developed is not sufficient to properly eject the cartridge.

It is, therefore, an object of this invention to overcome the above-mentioned disadvantages. An additional object of the invention is to provide a power actuated tool wherein the member to be driven may be breech loaded. A more specific object of the invention is to provide a power actuated tool wherein the piston and cylinder are removable so a fastener may be breech loaded. Yet, another object of the present invention is to provide a power actuated tool wherein the piston will be retained within the cylinder when the cylinder is removed and wherein the piston member is constrained from free flight during accidental firing of the tool. Still another object is the provision of guiding means to guide the fastener into proper place when it is breech loaded.

These and other objects of the present invention may be achieved through the provision of a power actuated tool including a barrel, removable piston and cylinder means within the barrel, and a hollow fastener guide having an internal surface with a tapered portion to guide the fastener into proper position.

The tool may also include piston means having a circumferential groove in its head portion, resilient retaining means positioned in the groove, and a circumferential groove in the internal surface of cylinder means adjacent one end thereof, whereby the piston means will be prevented from separation from the cylinder means by the expansion of the retaining means into the groove in the cylinder means.

The piston means may include ejection means having a first cylindrical portion with a diameter substantially equal to the internal diameter of the cartridge chamher. A second cylindrical portion may also be included with a diameter substantially equal to the internal diameter of a spent cartridge.

The above objects and advantages will be more readily understood by reference to a description of a specific embodiment of the invention and the accompanying drawing wherein:

FIGURE 1 is a side elevational view, partially in cross section, showing a power actuated tool made in accordance with the present invention;

FIGURE 2 is an enlarged view, partially in cross section, of the piston and cylinder means of the tool shown in FIGURE 1;

FIGURE 3 is an enlarged fragmentary view, partially in cross section, of the lower portion of the piston and cylinder means; and

FIGURE 4 is a partial sectional view taken in the direction of the arrows along the line 4-4 of FIGURE 1.

In the following description, the term forward is used to refer to a portion of the tool that is closer to the muzzle and the term rearward is used to refer to a portion of the tool that is closer to the handle or grip.

Referring to the drawings, FIGURE 1 shows a power actuated tool which includes a firing mechanism portion 2, a fastener driving portion 4, and a shield safety portion 6. A fastener member 8 is shown positioned in the fastener driving portion 4 to be driven by the tool into a desired member.

The firing mechanism portion 2 of the tool is substantially the same as the one described in US. Patent No. 2,945,236, and reference should be made to that patent for a description of the details of the various elements and their operation. Generally, the firing mechanism portion 2 may include an outer housing casing 10 having a pistoltype grip 12 and a trigger guard 14. A firing pin housing 16 may be mounted within the housing casing 10. A breech block 18 may be mounted for relative axial movement in the housing 16 and may be biased into a forward position by a spring 20.

The breech block 18 may carry a cocking rod 22 which coacts with a pawl 24 on the firing pin 26 when the tool is pressed against a surface to cock the pin 26. The firing pin may be biased by a spring 28. In addition, a trigger member 30 may be mounted for pivotal movement by pivot pin 32 and carry a sear 34 which acts to depress the pawl 24 when the firing pin 26 is cocked with the resultant release of the firing pin 26 for firing a cartridge.

The trigger member 30, however, is somewhat different from the one shown in US. Patent No. 2,945,236. In the preferred embodiment as shown in FIGURE 1, the sear 34 is a separate member, and is pivotally mounted in a groove in the rearward surface of the trigger member 30 by a pivot pin 35. In the normal position, the sear 34 has a portion abutting the bottom of the groove in the trigger member 36 whereby the sear is prevented from pivotal movement in a counterclockwise direction as viewed in FIGURE 1.

The fastener driving portion 4- of the tool may include generally a housing tube 36, a barrel housing collar 38, and a barrel member 40. A hollow cylinder member 42 may be disposed within the barrel member and a piston member 44 may be mounted for reciprocation within the cylinder member 42. The cylinder member 42 may be internally threaded as indicated at 45 to receive a breech plug 46 having an externally threaded portion 48 and a cartridge receiving chamber 50. It is to be understood that the breech plug 46 may be secured to the cylinder member 42 by any other suitable means such as welding, copper brazing, epoxy, swaging, or the like.

The forward end of the fastener driving portion 4 of the tool may include a buffer housing 52 secured to the barrel member and a muzzle bushing 54 secured to the buffer housing 52. A fastener guide 56 and buffer member 58 may be disposed within the buffer housing 52. A more detailed description of the fastener driving portion 4 of the tool will be set forth hereinafter.

The fastener driving portion 4 is connected to the firing mechanism portion 2 of the tool in the manner described in US. Patent 2,945,236. Generally, as shown in FIGURE 1, the firing mechanism portion 2 is pivotally connected to the fastener driving portion 4 by a slot mounted hinge pin 60 so that the two portions of the tool may not only be pulled apart, but also may be pivoted apart to a limited extent sulficient to permit loading the tool. In addition, the two tool portions 2 and 4 are connected in a locked position by means of lugs 62 on the outer portion of the barrel housing collar 38 coacting with female lugs 64 on the firing mechanism portion 2.

The rearward portion of barrel member 40 may include interrupted threads 66 to coact with interrupted threads 68 on the breech block 18 for locking the breech block 18 to the barrel member 40 and breech plug 46.

The shield safety portion 6 of the tool includes a safety shield 70, a safety shield tube 72, and a shield compression spring 74. Also included are barrel locking elements 76 which are adapted to coact with a groove 78 in barrel member 40 to prevent firing of the tool without the shield being connected thereto. An interlock pin 80 may also be provided to prevent operation of the tool if the fastener driving portion 4 and firing mechanism portion 2 are not properly locked together. Reference may be made to US. Patent 2,945,236 for a description of the operation of these elements.

Referring in greater detail to the fastener driving portion 4 of the tool, it will be seen that barrel member 40 has a substantially cylindrical internal surface 82. The hollow cylinder member 42 has a substantially cylindrical outer surface 84 and is mounted within the barrel member 40 with a sliding fit. The breech plug 46, which is attached to the rearward portion of the cylinder member 42, has a flange portion 85 which abuts the rearward end of the barrel member 40 and thereby, limits the forward movement of the cylinder member 42 relative to the barrel member 40.

The forward portion of the substantially cylindrical internal surface 86 of the cylinder member 42 includes a circumferential groove 88. As shown particularly in FIGURE 2, the groove 88 includes a portion 90 tapering to the greatest depth at the point nearest the forward end of the cylinder member and an abutement portion 92 having its surface at a sharp angle to the axis of the cylinder member.

The piston member 44, which is mounted for reciprocation in the cylinder member 42, includes a head portion 94 having a diameter substantially the same as the diameter of the internal surface 86 of the cylinder member 42. Extending forwardly from the head portion 94 is a ram portion 96 which protrudes from the forward end of the cylinder member 42 when the piston is in the firing position. The ram portion 96 of the piston member includes a tapered portion 98 immediately forward of the head portion 94 which tapers from a diameter equal to that of a head portion to a lesser diameter. The head portion 94 of the piston member 44 may include a circumferential groove 100. Resilient retaining means 102 may be mounted within the groove 100. The resilient retaining means 102 may be a split spring steel ring, or a ring of polyfluoroethylene, silicon rubber, or

any other suitable material. The retaining means 102 should be of such size that it is compressed between the groove and the internal surface 86 of the cylinder member 42.

An ejector member 104 may be connected to the rearward end of the head portion 94 0f the piston member 44. The ejector member 104 may include a cylindrical portion 106 which has a diameter substantially equal to the diameter of the cartridge receiving chamber 50 in the breech plug 46 and a short reduced portion 108 having a diameter substantially equal to the internal diameter of a cartridge to be used in the tool.

The forward portion of barrel member 40 is externally threaded as indicated at 110 to receive the internal threads 112 of the buffer housing 52. The buffer housing 52 includes a first hollow cylindrical portion 114 and a seeone reduced hollow cylindrical portion 116. The provision of the reduced portion 116 results in a circumferential shoulder 118 in the internal surface of the buffer housing 52.

The fastener guide 56, which is mounted within the buffer housing 52, includes a portion 120 having a cylindrical external surface 122 and an internal tapering surface 124 which converges from a diameter substantially equal to that of the internal surface of a barrel member to a diameter slightly larger than that of a fastener. Fastener guide 56 may also include a hollow elongated cylindrical forward portion 126 having an external diameter substantially equal to the internal diameter of the reduced cylindrical portion 116 of the buffer housing 52. The two portions 120 and 126 of the fastener guide 56 may be joined by a fillet to provide a shoulder 128 on the external surface of the guide 56. As shown in FIGURE 1, the forward portion of cylindrical portion 126 of the fastener guide 56 extends into reduced cylindrical portion 116 of the buffer housing 52.

The buffer member 58 is positioned about the fastener guide 56 and extends from the shoulder 118 on the buffer housing 52 to the shoulder 128 on the fastener guide 56. The buffer member 58 may be fabricated from any suitable resilient material.

The hollow muzzle bushing 54, which is threadedly connected to the internal surface of the reduced cylindrical portion 116 of the buffer housing, may include in its rearward portion a frusto-conical tapered opening 130 which has its smallest diameter equal to that of the fa tener. The forward end 132 of the fastener guide 56 is spaced from the rearward end 134 of the muzzle bushing 54. It is to be understood that various types of muzzle bushings may be used, depending upon the particular fastening operation to be formed.

In operation, after the tool has been fired in the manner described in US. Patent 2,945,236, the operator may unlock the tool and separate the firing mechanism 2 from the fastener driving portion 4, whereby breech plug 46 and the spent cartridge 136 will be exposed. The operator may then remove the cylinder member 42 and piston member 44 from the barrel member by grasping the flange portion 85 of the breech plug 46 and pulling outwardly.

The piston is prevented from disengagement with the cylinder by virtue of the circumferential groove 88 in the internal surface 86 of cylinder member 42 and the resilient retaining means 102. As shown in FIGURE 3, as the piston moves downwardly, the retaining means 102 will expand into groove 88 as it passes the tapering portion 90 and then will become lodged against the abutment portion 92 of the groove whereby further forward movement of the piston relative to the cylinder member is prevented.

The cartridge 136 may be ejected by positioning the forward end of the ram portion 96 of the piston member 44 against a suitable surface and pushing the piston member 44 rearwardly in the cylinder member 42 into the position shown in FIGURE 2. Air will be trapped in the space 138 between the head portion 94 of the piston member 44 and cartridge 136 and, as the reduced portion 108 of the ejector member 104 engages and dislodges the cartridge shell 136, the compressed air will serve to completely eject the cartridge.

An ejector cup 140 is provided to present a suitable surface against which the end of the piston member may be pushed during the ejection operation. As shown in FIGURE 4, the ejector cup 140 includes a frusto-conical internal surface 142. The cup 140 is attached to the tool by hinge pin 60 which extends through the cup 140 and has a head with a tapered portion 144 in engagement with a portion of the internal surface 142 of the cup 140.

After ejection of the spent cartridge 136, the piston member 44 will be held in its retracted position with the head portion 94 adjacent the breech plug 46 by virtue of the frictional engagement of the retaining means 102 with the internal surface 86 of the cylinder.

The operator may then insert a new fastener in the breech end of the barrel member 40. The fastener will be guided into proper position within the tool by virtue of the tapering portion 90 of the fastener guide and the frusto-conical tapered opening 130 in the muzzle bushing 54.

One type of fastener member that may be used with the tool of the present invention is shown in FIGURE 1. The fastener member 8 has an enlarged threaded portion 146 at one end and a plastic tip 148 having an annular flange 150 at the other end. The flange 150 is in frictional engagement with the internal surface of the muzzle bushing 54.

After the piston member 44 and cylinder member 42 are reinserted in the barrel member 40, a new cartridge 152 may be positioned in the cartridge-receiving chamber 50. The cartridge may include a casing 154 having its forward portion 156 closed by a star crimp. Upon insertion of the cartridge, the forward portion 156 will contact the short reduced portion 108 of the ejector member 104, pushing the piston member 44 forward into proper firing position. The length of the ejector member 104 controls the spacing of the head portion 94 of piston member 44 from the breech plug 46. By proper selection of the length of the ejector member 104, the power level of the tool may be controlled.

The provision of the short reduced portion 108 of the ejector members serves to permit the passage of the gases into the space 158 behind the head portion 94 of the piston member immediately upon the explosion of the cartridge. Since the cartridge does not extend through the breech plug 46, if the reduced portion 108 of the ejector member was not provided, the cylindrical portion 106 would be positioned in the cartridge receiving chamber 50 and the gases generated by the activation of the cartridge could not pass immediately into the space 158 behind the head portion 94 of the piston member 44. Thus, the gases would be acting upon the end of the cylindrical portion 106 which would be undesirable.

In the event of an overdrive of the piston, the tapered portion 98 will contact the internal tapering surface 124 of the fastener guide 56. The forward movement of the fastener guide 56 is resisted by the buffer member 58 which is slightly compressed and absorbs the excess energy. The spacing between the forward end 132 of the fastener guide 56 and the rearward end 134 of the muzzle bushing 54 permits the slight movement of the fastener guide 56 as the buffer 58 absorbs the excess energy.

Overdrive of the piston member 44 is further prevented by the provision of vent holes 160 in the barrel member 40. As the end of the head portion 94 of the piston member 44 passes the holes 160, the gases generated by the firing of the cartridge may pass out of the cylinder member 42 into suitable escape channels in the barrel member 40.

From the above description, it Will be obvious that the tool of the present invention presents many advantages.

The provision of the removable piston and cylinder permits breech loading of a fastener member.

The particular configuration of the fastener guide serves not only to properly position the fastener when it is loaded, but also serves as an abutment for the piston and coacts with the buffer member to prevent severe overdrive of the piston.

The particular ejector member associated with the tool provides for proper ejection of a spent cartridge shell by direct contact as well as utilization of compressed air formed in the cylinder member. The ejector member also serves to provide the proper power level of the tool.

It will be obvious that other embodiments may occur to those skilled in the art. It is to be understood that the above description of the preferred embodiment is not intended as a limitation of the scope of the present invention, but rather, various alterations and modifications may be resorted to without departing from the broader scope of the invention as defined by the following claims.

What is claimed is:

1. A power-actuated piston tool comprising barrel means having an axially extending bore, hollow cylinder means removably disposed within said bore, piston means axially slidable within said cylinder and including a head portion and a ram portion, cartridge-receiving means secured to said cylinder means at one end thereof, a first circumferential groove in the internal surface of said cylinder means adjacent the other end thereof, a second circumferential groove in said head portion, and resilient means positioned within said second circumferential groove, said resilient means being compressed between said second circumferential groove and the internal surface of said cylinder and adapted to expand into said first circumferential groove to prevent accidental withdrawal of said piston means from said cylinder means.

2. The piston tool of claim 1 wherein said first circumferential groove includes a tapering portion tapering to its greatest depth toward said other end and an abutment portion at the end of said tapering portion closest to said other end, said abutment portion having a surface at a sharp angle to the axis of said cylinder means.

3. A power-actuated piston tool comprising barrel means having an axially extending bore, hollow cylinder means removably disposed within said bore, piston means axially slidable within said cylinder and including a head portion of reduced diameter and a ram portion, cartridge receiving means secured to said cylinder means at one end thereof, and fastener guide means extending forwardly from said barrel means adjacent the other end of said cylinder means, said fastener guide means including an axially extending bore, that portion of said bore of said fastener guide means closest to barrel means tapering convergingly from a diameter at least as great as the internal diameter of said barrel means to a diameter less than the internal diameter of said hollow cylinder means.

4. The piston tool of claim 3 further comprising a buffer housing secured to said barrel and extending forwardly therefrom, a hollow muzzle bushing attached to said buffer housing and extending forwardly therefrom, said buffer housing having a first hollow cylindrical portion and a second reduced hollow cylindrical portion, said fastener guide means being disposed within said first hollow cylindrical portion, and buffer means interposed between said fastener guide and said buffer housing, said ram portion of said piston means having a tapered portion adjacent said head portion which corresponds to the taper of said bore in said fastener guide means.

5. The piston tool of claim 4 wherein said muzzle bushing includes a tapered opening at its end closest to said fastener guide and wherein said fastener guide is axially spaced from said muzzle bushing.

6. The piston tool of claim 5 wherein said tapered opening converges to a diameter smaller than the internal diameter of said cylinder means.

7. A power-actuated piston tool comprising barrel means having an axially extending bore, hollow cylinder means removably disposed within said bore, piston means axially slidable within said cylinder means and including a head portion and a forwardly extending ram portion, cartridge receiving means secured to said cylinder means at one end thereof and having a cylindrical cartridge-receiving chamber therein, ejector means extending from said head portion of said piston means toward said cartridge-receiving chamber, said ejector means comprising a first cylindrical portion having a diameter substantially equal to the diameter of said cartridge chamber and a second reduced cylindrical portion extending from said first cylindrical portion.

8. The piston tool of claim 7 wherein said piston means is axially slidable in said cylinder means between a driving position and a driven position and the ram portion of said piston means extends from the other end of said cylinder means when said piston means is in said driving position.

References Cited by the Examiner UNITED STATES PATENTS 3,016,539 1/1962 Marsh et a1 227-40 GRANVILLE Y. CUSTER, JR., Primary Examiner. 

1. A POWER-ACTUATED PISTON TOOL COMPRISING BARREL MEANS HAVING AN AXIALLY EXTENDING BORE, HOLLOW CYLINDER MEANS REMOVABLY DISPOSED WITHIN SAID BORE, PISTON MEANS AXIALLY SLIDABLE WITHIN SAID CYLINDER AND INCLUDING A HEAD PORTION AND A RAM PORTION, CARTRIDGE-RECEIVING MEANS SECURED TO SAID CYLINDER MEANS AT ONE END THEREOF, A FIRST CIRCUMFERENTIAL GROOVE IN THE INTERNAL SURFACE OF SAID CYLINDER MEANS ADJACENT THE OTHER END THEREOF, A SECOND CIRCUMFERENTIAL GROOVE IN SAID HEAD PORTION, AND RESILIENT MEANS POSITIONED WITHIN SAID SECOND CIRCUMFERENTIAL GROOVE, SAID RESILIENT MEAN BEING COMPRESSED BETWEEN SAID SECOND CYLINDER GROOVE AND THE INTERNAL SURFACE OF SAID CYLINDER AND ADAPTED TO EXPAND INTO SAID FIRST CIRCUMFERENTIAL GROOVE TO PREVENT ACCIDENTAL WITHDRAWAL OF SAID PISTON MEANS FROM SAID CYLINDER MEANS. 